1. Technical Field
The invention relates to a process for plugging an abandoned well and more particularly to a process for plugging an abandoned well with a polymer gel wherein the wellbore penetrates a subterranean hydrocarbon-bearing formation.
2. Description of Related Art
Wells employed in the production of oil and gas are abandoned inter alia because they reach the end of their useful life or they become damaged beyond repair. State and federal regulations require that abandoned wells be plugged to protect safety and environmental interests. The well is commonly plugged by pumping Portland cement into the wellbore and curing the cement in situ.
Formulation of Portland cement in the field is largely a product of trial and error by field personnel to meet irregularities in the cementing composition and the downhole environment. Cement quality control is difficult to achieve under such conditions. As a result, Portland cement cured in situ can exhibit cracking, shrinking, or poor adhesion to wellbore tubulars. An imperfect Portland cement plug can enable undesirable fluid flow through the wellbore via leaks along or through the cement.
A process is needed which employs a plugging material having a broad range of highly controllable and predictable set-up times providing ease of operation and design at a relatively low cost. A process is needed employing a substitute material for Portland cement in conventional plugging processes which forms a more effective plug and seals the wellbore indefinitely.